1. Field
The present invention relates to a power source device that supplies a stabilized output voltage to a load section, for example, of a semiconductor device incorporated into server equipment or network equipment, and to an output voltage stabilizing method used therein.
2. Description of Related Art
Recently, the development of semiconductor devices such as LSIs (Large Scale Integrations), CPUs (Central Processing Units), and FPGAs (Field Programmable Gate Arrays) has made rapid progress and a reduction in operating voltage and increases in current handled and operating speed of the semiconductor devices as mentioned above have been rapidly promoted accordingly.
Therefore, as for a power source device that supplies power to the load section of the semiconductor device as mentioned above, requirements for a performance of supplying a stabilized output voltage to the load section of the semiconductor device have become extremely strict.
In order to meet the above mentioned requirements, high-speed response characteristics to a fluctuation in load of the load section have been strongly desired in the power source device, so that making higher a switching frequency has been promoted as a countermeasure thereto. However, in reality, making the switching frequency higher is now reaching its limit from the viewpoints of power conversion efficiency attained and heat generated.
There are known techniques in which if a reduction in output voltage due to the occurrence of a large amplitude and high speed fluctuation in load of the load section of the power source device has been detected, an output inductance is made variable to stabilize the output voltage which has been fluctuated due to the occurrence of the fluctuation in load of the load section (see, for example, Japanese Laid-Open Patent Publication Nos. 2005-168157, 2004-274904 and 2003-88114).